1. Field of the Invention
The present invention pertains to measurement instruments. More particularly, this invention relates to a measurement instrument display-based control knob.
2. Background
Various measurement instruments are known in the art, such as oscilloscopes, spectrum analyzers, and reflectometers. Measurement instruments include instruments that generate test signals, instruments that merely measure or sample signals, and combinations thereof. Measurement instruments are used in a wide variety of applications, such as measuring engine vibrations, measuring electronic device voltages, measuring brain waves, etc. Historically, measurement instruments are analog devices, however, increasingly measurement systems are constituted with digital components. Furthermore, increasingly graphical user interfaces (GuIs) are being employed to assist users in control and operation of the instruments.
Measurement instruments typically provide a variety of user-controllable parameters in order for a user to "tune" the instrument properly to whatever signal(s) the user is trying to measure and to display the signal(s) in a manner useful to the user. Examples of such parameters include the center frequency of a spectrum analyzer, the vertical position of an oscilloscope trace, etc. Different mechanisms currently exist to allow users to adjust these parameters.
One such mechanism, illustrated in FIG. 1a, is referred to as a "slider". A slider is typically a vertical or horizontal line 101 along which a slide box 102 can be moved by a user. Values are changed by moving the slide box 102 along the line 101 (e.g., "clicking" and "dragging" the box 102 with a pointer). However, one problem with sliders is the inability to make fine adjustments. Rather, the user is limited by how finely he or she can move slide box 102 in a "click and drag" manner, as well as how "sensitivity" parameters for the slider are set up.
Another such mechanism, illustrated in FIG. 1b, are up and down arrows 106 and 107 that allow a user to increment a value 108 by selecting up arrow 106 or decrement the value 108 by selection down arrow 107. Selection of one of the arrows 106 or 107 is typically done by clicking the appropriate arrow with a pointer. However, problems with such arrows include the inability to allow different rates of adjustment (rather, a user is limited to clicking one of the arrows 106 or 107) and the inability to provide graphical feedback of the change in value (rather, only the numeric value is displayed).
Another such mechanism, illustrated in FIG. 1c, is referred to as a "type-in" value. A type-in value box 115 displays a current value for a parameter (the value 132 in the illustrated example). A user can alter the current value by simply entering a new value, such as by typing it on an alphanumeric keyboard. However, problems with type-in values include the inability to provide graphical feedback of the change in value (rather, only the numeric value is displayed), and the inability to provide any GUI-oriented inputs (rather, only typing in a particular value can be done).
Another such mechanism, illustrated in FIG. 1d, is referred to as a "scroll bar". A scroll bar is typically a vertical or horizontal "bar" 121 through which a user can drag a box 123 to alter parameter values. Additionally, values can be incremented by pressing an up arrow 127 or decremented by pressing a down arrow 125.
However, one problem with scroll bars, as well as each of the other mechanisms in FIGS 1a-1c, is that they lack the intuitive clockwise vs. counterclockwise mapping to increasing value vs. decreasing value found in manual control knobs to which people are accustomed. Furthermore, each of the mechanisms illustrated in FIGS 1a-1d lacks the intuitive "stops" or "boundaries" in the clockwise and counterclockwise directions found in manual control knobs.
Thus, an improved parameter adjustment mechanism is needed. As will be discussed in more detail below, the present invention achieves these and other desirable results.